According to demands of the marketplace, a need for a high resolution of the quality of an image of an image pickup device such as a video camera or a monitoring camera has increased. For the high resolution of the image quality, an image pickup element becomes highly dense. Because a focal depth of the image pickup device is narrow when the resolution is high, it is necessary to accurately adjust a focal distance to properly adjust the focus of an image.
For this, it is necessary to first accurately adjust a flange focal length, which is a distance from a mounting surface of a lens to a light-receiving surface of the image pickup element. Patent Literature 1 discloses technology related to a position adjustment device of a solid-state image pickup element that adjusts the flange focal length. In addition, Patent Literature 2 discloses technology related to a holding device of an image pickup element that makes the center of an optical axis of the image pickup element consistent with an optical axis of a lens.